Process of treating animal fibers and product thereof



Patented Jan. 13, 1948 PROCESS OF TREATING ANIMAL FIBERS AND PRODUCTTHEREOF Milton Harris. Foundation,

Bethesda, Md., assignor to Textile Washington, D. 0., a corporation oithe District of Columbia No Drawing. Application October 17, 1941,

- Serial No. 415,496

11 Claims.

This invention relates to the treatment of materials which containkeratin and more particularly to animal fibers of the epidermal type,such as Wool, hair and fur. With greater particularity the inventionrelates to such materials which contain keratin and which arecharacterized by having a plurality of disulfide (or cystine) linkagesin the molecule. This invention also relates to the product produced bythe treatment which will be hereinafter described. It is known that wooland hair and like fibrous materials which contain keratin containmolecules which are protein-like molecules believed to consist of aminoacids joined'through amide (peptide) linkages to form long chainstructures called poly-peptides. It is therefore believed that suchdissimilarities as are found in varying fibers of this type are dueprobably to variations. in the proportions and arrangement of theconstituent amino acids, to difierences in the lengths and arrangementsof the poly-peptide chains and to the presence of linkages other thanpeptide. This invention relates primarily to one of the linkages, thedisulfide linkage, of the amino acid cystine and to the propertiesimparted to the animal fiber by modifying the disulflde linkage withoutdisturbing any more than possible the other linkages of the molecule.

It is known that animal fibers which contain keratin, such as wool andhair and the like, are subject to attack by insects, such as mothlarvae, and are likewise subject to shrinkage when subjected totreatment by hot water or steam, particularly when the water has beenmade alkaline as by the addition of soap. Further, such animal fibers intheir natural state, or when cleaned or subjected to chemical treatmentwhich does not modify the chemical nature of the fiber, are subject tobiological degradation which may be caused not only by insects, such asmoth larvae, for example, but also by bacteria, molds and enzymes.Furthermore, certain of such animal fibers, of which wool is an example,are not as stable as might be desired when subjected to sunlight. Inaddition, certain of the animal fibers such as wool, when made intofabrics, are subject to staining when placed in contact with metals. It

is believed that such staining is the result of a,

reaction between the metal, of which silver is an example, and thesulfur of the molecule of the animal fiber.

Attempts have been made to reduce the susceptibility of such materialsto attack. by insects, such as moth larvae, by utilizing variouschemical treatments, generally the surface treatment of the fibers withchemicals known to be repugnant to or suspected of being toxic towardthe insect. Other types of treatment have been resorted to such asfumigating the fibers or fabrics made therefrom with camphor,naphthalene or halogen derivatives of aromatic compounds. None of'thesetypes of treatment have, as far as is known, been really successful inrendering the animal fibers permanently insectproof and few, if any, ofthe treatments have any marked effect in increasing the resistance ofthe animal fibers to other types of biological degradation, such asresulting from bacteria, molds and enzymes. It is believed that at bestsuch treatments are but transient ones, the benefit of which is soonlost when the animal fibers or the fabrics made therefrom are subjectedto repeated washing or drying cleaning.

Attempts have been made to reduce or elimi'-.

hate the shrinkage and felting tendency of such:

animal fibers by subjecting the fibers to chemical treatment with eitheroxidizing or reducing agents. So far as is known, none of the treatmentswhich have heretofore been attempted have resulted in reducing thenatural shrinkage of animal fibers to any'marked degree without leavingthe molecule, and particularly the sulfur thereof, in a highly reactiveform which renders the fiber more susceptible to damage and degradationin service. There is a further disadvantage to such chemical treatmentof the wool molecule. So far as is known, there has been no suchtreatment attempted which has not resulted in degrading a veryappreciable portion'of the animal fiber through disruption of otherlinkages as well as some of the disulfide linkages.

This invention has for one of its objects the treatment of animal fibersof the epidermal type and fibers which contain keratin, which are char.

acterized by having a plurality of disulfide (or cystine) linkages inthe molecule in a series of easily controlled and readily duplicatedsteps to produce a, modified animal fiber which has very distinctadvantages and which is obtained without appreciable or markeddegradation of linkages in the molecule other than the disulfidelinkages.

Another object of my invention is the production of a modified animalfiber of the type described which is resistant to biological degradationsuch as that resulting from insects, bacteria, molds, enzymes, with apermanency not hitherto attained. A still further object of theinvention is the production of such a modified animal fiber which ischaracterized by resistance to alkalies such as soaps and to chemicalreagents such as the sulfites which are frequently used in strippingwool. It is an object of this invention to produce a modified animalfiber of the type described which is characterized by stability towardslight and by resistance to staining when subjected to contact withmetals which readily form sulfides, such as, for example, silver.

In one of its broad aspects, this invention contemplates the treatmentof animal fibers of the epidermal type, and which contain keratin, suchas wool, hair, and fur, as well as materials fabricated partially orcompletely therefrom, by subjecting the material to the action of areducing agent while controlling the pH value of the reaction. Thistreatment disrupts some or all or a predetermined proportion of thedisulfide groups in the molecule and converts the said disulfide groupsinto sulfhydryl groups. The so treated material is then reacted with anagent which contains a desired substituent reactive with the hydrogen ofthe sulfhydryl groups, to form a bis-thioether linkage. There resultsfrom this novel treatment a novel product which has been found to beresistant to biological degradation, resistant to alkalies, stabletowards light, and resistant to staining by metals, as well, as havingother desirable properties.

The following example is given by way of illustration to disclose onemanner in which this novel process may be employed with an animal fibercontaining keratin, such as wool:

A given amount of wool was emerged in such a volume of approximately 0.2M. thioglycolic acid solution which had been brought to pH6 byanysuitable alkali such.as NaOH, that the molar ratio of thioglycolic acidto the disulfide (or cystine) sulfur in the wool was about 20 to 1. Themixture was allowed to stay at about room temperature, 1. e., about 20C. to about 30 C. for about 24 hours. The wool was then removed from thesolution, washed with water to remove the excess thioglycolic acid andany oxidation products produced as the result of the treatment. The woolso reduced by thioglycolic acid could then be dried and stored forsubsequent treatment or it could then be subjected to subsequenttreatment in its moistened condition. In either event, it has been founddesirable to wash the reduced wool thoroughly with 95% ethyl alcohol andthen rinse the so washed wool with water. The reduced wool was thenplaced in a 0.1 M, potassium phosphate buffer solution having a pH of8.0 in which had been dissolved or suspended the desired alkylatingagent. In this illustrative example, the alkylating agent istrimethylene dibromide. bromide, CH2Br--CH2CHzBr, was present in about0.002 mol and 100 ml. of buffer solution for each gram of wool. The woolin the presence of the alkylating agent and buffer solution was agitatedto enhance thorough contact between the trimethylene dibromide and thereduced wool. The treatment was continued until a sample of the woolwhen treated with nitroprusside reagent failed to give a positive testfor y the sulfhydr l group. The modified wool was then removed from thereaction bath. washed with water and dried in the air. Analysis of theuntreated; i. e., original, wool showed a cystine content of 12% whilethe cystine=content of the reduced and alkylated wool produced by thisillustrative example was 4%. The nitroprusside test was performedinaccordance with the prooedure described in: Zeitschrift P111810 Chem..

The trimethylene di- K. A. H. Morner, vol. 28, page 611 (1900). Thecystine content of each analysis was determined by the method ofanalysis described in Public Health Reports 86 (1930) and Research PaperRP 810, Journal of Research of the National Bureau of Standards, volume15, 1935.

The process illustrated in the above example may be subjected to manyvariations; It has been found desirable to maintain the hydrogen ionconcentration of the reaction mixture during the reducing step of thetreatment preferably below about pH 9. The preferred range is betweenabout pH 9 and about pH 4. However, if precautions are taken with regardto the length of treatment and to the temperature of the reducing bathas well as to the concentration of the reducing agent, it has been foundpossible to effect the reduction of the disulfide (or cystine) linkagesat hydrogen ion concentrations between about pH 0.0 and about pH 12.0.Nevertheless, it has been found that with an alkalinity above about pH 9there will be undesirable side reactions and an undesired amount ofdissolving of the fiber in an alkaline reducing bath of this degree ofalkalinity. Since it is desired to perform the process of thisapplication with a mini- -mum amount of undesired side reactions and abelow about pH 9. It has also been found that the undesired sidereactions and undesired solution are minimized to a far moresatisfactory extent by carrying out the reducing step of the process ina neutral or acid medium preferably below pH 7 and more desirably atabout pH 5.

During the alkylation step of the process it is preferred to maintainthe hydrogen ion concentration at a pH of between about 7.5 and about8.0 as determined in aqueous media. Alkylation may be satisfactorilyaccomplished under hydrogen ion concentrations between about pH 7.0 andabout pH 9.0 provided that in the extremities of this range dueprecautions are taken with regard to temperature, concentration ofreagents, length of time and other operating conditions. It isunderstood that prior art attempts to reduce wool have been made with awide variety of reducing agents. It has been found, however, indeveloping the invention described in this application that reducingagents such as mercaptan acids, for example thioglycolic acid,mercaptans, for. example H28 or NaSH, more particularly alkylmercaptans, such as butyl or ethyl mercaptans, and mercaptan giycols,such as beta-mercapto' ethanol, are unique in their ability to reduceanimal fibers, such as wool, without causing undesired solution ordegradation under the conditions of reduction. The said reducing agentsare also unique in their ability to disrupt the disulfide (cystine)linkage and produce sulfhydryl groups from both sulfur atoms in thedisulfide linkage under the conditions of reduction.

In the illustrative example there has been described the performing ofthe reduction step at room temperature and over a period of about 24hours. Lower or higher temperatures, such as ab0ut-0 C. to about C., maybe employed and longer or shorter periods of exposure to the reducingagent may be employed if desired. It has been found that in general withhigher temperatures a shorter period of exposure is desired and withlower temperatures a longer period of exposure to the reducing agent maybe employed.

ance of this process to subject the animal fiberp for example wool,agent under such riod of time as to of less than all of the disulflde(or cystine) linkages. Thus, for example, a fraction of the di sulfidelinkages such as, for instance,*25% thereof or 50% thereof or75%thereof; may be reduced with the creation of the sulfhydryl groupsand the reduction then stopped to permit further treatment.

The concentration of the reducing agent is of importance. It has beenfound desirable to use at all times a considerable excess of the amountof reducing agent over and above that theoretically necessary to reduceall the disulfide (cystine) linkages of the molecule. It is preferred touse at least 20 times the amount of reducing agent theoreticallynecessary. It has been determined that the amount of reduction increasedrapidly with someincrease in the concentration of the reducing agent.Thus, there was a noticeable rapid increase when the reducing agent wasin-. creased from 0.01 to 0.2 M. There was an increase, although a lessmarked one, between 0.2 M. and 0.5 M. Increase in the concentrationbeyond 0.5 M. had relatively less efiect.

In preparing for and accomplishing the alkylating step so as to replacethe sulfhydryl hydrogen atoms with alkyl or other organic groups, thehydrogen ion concentration of the reaction medium may be adjusted in anywell known manher, as by means of a bufier solution. As buffering agentsthere may be employed borax, soda ash, phosphate buflfers and the likeand the bufferingsolution may be further modified by any desiredalkaline compound which will have the efl'ect of creating the desireddegree of alkalinity so that the pH of the alkylating medium is at theproper figure. v

For a clearer understanding of the alkylating step which is employed inaccordance with this invention, the following equations may be referredto:

to the action of the reducing conditions and for such a pem v 1 w-ss-w'zns-cm-ooon' a W-SH HS W s-om-cooH), in which W and W representdifferent portions of the wool molecule which are linked together thereduced wool from Equation I is treated with an alkylating agent of thetype contemplated by this invention as, for example, trimethylene dibromide, the hydrogen atoms of the sulfhydryl effect the deliberatereduction employed successfully;

trimethylene dibromide,

6 groups are replaced with the alkyl nucleus and form a disulflde alkyllinkage as shown by the following equation:

A alkylating agents, a wide variety of compounds may be employed. Ingeneral, dihalide compounds, such as alkyl dihalides, substituted alkyldihalides, aralkyl dihalides and substituted aralkyl dihalides will befound useful. Some alkaryl compounds such as p-dichlor-dimethyl dibenzolare reactive. In general, it may be said that any alkyl, substitutedalkyl, aralkyl, or substituted aralkyl compound having at least tworeactive halogen atoms may be employed with success. Thus, aliphaticalkylene or poly-alkylene dihalides, such as methylene andpoly-methylene dihalides, have been tested and found useful. As examplesof these are: methylene dibromide, CHzBrz; ethylene dibromide, cHeBr-cHzBr; CEBr-CHz-CHzBr; tetramethylene dibromide CHzBr-(CHzM-CHzBr anddihalides of a similar nature which include halogens other than bromine,for example, the chlorides and iodides. Examples of these are: methylenedi-iodide, CHzIz; and ethylene dichloride, CHzCl-CHzCI. Compoundsfalling under the same general type as those used above for the purposeof illustration but bearing other functional groups as side chains,havebeen tested and found useful. Dihalides bearing hydroxyl groups orcontaining ether linkages have been dihalides bearing hydroxyl groupshave the uble in water. Examples of these are: 1,3-dichlorisopropanol,CH2CICHOHCHzCI 1,3-dibromisopropanol, CH2BrCHOHCHzBr 2,3-dibrompropanol,CH2BrCHBrCHeOH Dlchlorodiethyl ether, [ClCHzCHz'|zO Dichlorodiisopropylether, ICICH2CH(CH1)]2O Triglycol dichloride,Cl-CHz-CHz-O-CH2CHz-O-CH:CHz-Cl Some compounds having one or more of thereactive halogens replaced with reactive oxygen are reactive, forexample, epichlorohydrin Certain compounds have been tested and found tobe useless or of such little use as to render them undesirable. Thus,acyl halides derived from dibasic acids, of which phosgene is anexample, have been found to be useless. Compounds of this type andcertainly the simpler homologues, such as phosgene, do not react withreduced Wool to produce the desired alkylated cross-linkages. Certain ofthe higher homologues of phosgene have not been tested but even if theywere reactive with reduced wool, the products would be fundamentallydifferent from those contemplated by this invention. This inventioncontemplates alkyl conjugated thioethers. The acyl halides, of whichphosgene is an example, would produce thioesters and not thioethers.Thioester linkages, among other things, are much less stable towardsalkali and advantage of being solhave been found to be unreactive. Amongthese are dihalides containing unreactive halogen atoms such as the arylhalides. An example of this type is p-chlorobenzyl chloride ClaCH-COOHare illustrative.

It will be observed that the compounds given above by way ofillustration fall in general under groups such as alkyl, substitutedalkyl, aralkyl,

and substituted aralkyl dihalides or alkaryl hal-' ides which may beeither saturated or unsaturated, and which are in general characterizedby having in the molecule a plurality of reactive halogen atoms whichwill react with the hydrogen of the sulfhydryl groups formed bydisrupting the disulfide linkages of the wool. The compounds have afurther characteristic in that they are capable of reacting with both ofthe sulfhydryl groups formed by disrupting the disulfide linkages of thewool and thereby reforming the disulfide linkage as what might be calledan alkylated disulfide linkage.

It has been found that the alkylating step of this process and thecompleteness of reaction may be controlled by changing the solventmedium employed during the alkylating step. An aqueous medium,particularly one which contains a buffering agent, has been found to bevery effective in this stage of the process, especially where thealkylating reagent is normally liquid. However, it has also been foundthat an alcoholic solution containing, for example, ammonia or othersoluble basic reagent, is an effective medium for the alkylating step.There may be employed, however, other non-aqueous yet suitably inertsolvents such as benzol, toluol, methyl alcohol, ethyl alcohol, propylalcohol, cyclohexane, aliphatic liquid hydrocarbons and mixtures thereofsuch as naphtha. v

The reduction and subsequent alkylation of the animal fiber has beenillustrated in this specification by means of wool. It has been foundthat the process may be employed on wool fibers, wool yarn, wool cloth,piece goods, or unfabricated wool in the bulk. While wool. has been usedas a representative example of the epidermal type of animal fiber towhich my invention relates, other keratin-containing and epidermal typefibers, and materials fabricated therefrom, such as fur and hair, may betreated by this process.

While it is not desired that any theory be advanced as a limitation uponthe invention disclosed herein, it is believed that, based upon previousknowledge of wool and upon its reported molecular structure,'wool andall other animal fibers of the epidermal type which contain keratin havecomplex molecular structures. It is known that keratin is a complexmolecule of the type C'inHnNoopsq, in which m, n, o, p and q areintegers, which is believed to be united in multiple complex side chainslinked together by a plurality of disulfide (or cystine) linkages. Forthe sake of simplicity, it is believed that the keratin molecule may beillustrated by the following formula: v

in which W and W are identical or substantially similar side chaincomplexes containing carbon. hydrogen, nitrogen and oxygen together withsome possible impurities, i. e., W and W represent the portions of thewool molecule to which the disulfide linkages-are attached, and a is anumber greater than one.

The reduction step of the process affects the disruption of thedisulfide linkages,'i. e., the cystine, and form cysteine, i. e.,sulfhydryl, groups. Consequently, after the reduction step, that is,after the disruption of the disulfide linkages, the wool molecule may berepresented as follows:

where the reduction has been practically complete. In this formula W andW are as in (III) above and represent the portions of the wool moleculeto which the now disrupted disulfide linkages are attached and a is anumber greater than one. Where the reduction has not-been complete, themolecule may be represented as follows: I

where W and W are as in (I) and (II) above and represent the portions ofthe wool to which the disulfide linkages were originally attached. b andc are numbers the sum of which equals the numher a which is greater thanone.

The alkylating step of this process accomplishes the replacement of thehydrogen atoms of the sulfhydryl groups of the reduced wool with theselected nucleus. Thus, where trlmethylene dibromide was used as thealkylating agent, the final product will be as shown in Formula II oncolumn 6 of this specification. This may be more broadly stated as:

where-R represents an alkyl, a substituted alkyl, an aralkyl, or asubstituted aralkyl nucleus, and b and c are numbers the sum of whichequals the number a which is greater than 1.

The process which has been described above possesses a number ofdistinctly novel features. The reduction step is readily controlled andwhen following the teachings of this invention may be performed with aminimum of undesired degradation and solution of the animal fiber beingtreated. The alkylating step is likewise one which may be readilycontrolled and which results in a new and useful product. The resultantalkylated product may be considered an alkylated animal fiber, forexample, an alkylated wool. The alkylated wool has been found to be farsuperior to ordinary wool with regard to a number of importantconsiderations. Thus, it is more renormal, is utilized and the cationembraces a novel and degradation caused in untreated wool by sunlight.It is more resistant to shrinkage and ielting than is untreated wool.The alkylated wool has little, if any, odor, whether dry or wet.Hotwithstanding this absence oi. odor, it is more resistant to mothlarvae than is untreated wool or wool which has been treated with manyof the prior art so-called mothprooflng agents, some 01' which impartrepugnant and permanent odors to the wool or fabric. The alkylated woolis resistant to reducing agents and furthermore is less susceptible todiscoloration when exposed to direct contact with tarnishing metals suchas silver or the insides of jewelry boxes. It has been found that thealkylated wool may be dyed as readily and in some instances much morereadily than untreated wool. There are, however, several even moreimportant properties. The alkylation of the wool when carried out inaccordance with this invention produces an animal fiber in whichelasticity characteristics are comparable to the original fiber, and thestress-strain characteristics are very markedly retained.

Of even more importance than the other benefits which have beenillustrated above is the relative insolubility of the alkylated wool inalkaline solutions and in reducing solutions. The laundering of wool inthe presence of soap is, in its simplest aspect, the treatment of thewool with an alkaline medium. Untreated wool is generally degraded andshrunk in laundering due to its lack of resistance to the alkalinity ofthe soap solution. Similarly, in preparing wool for fabrication, thestripping agents, such as the sulfites, have a marked degrading effecton the wool. Toward both types of treatment. the alkylated wool producedby this invention shows very marked superiority over untreated wool. Inthe normal laundry practice, a soap solution having a pH of and atemperature appreciably above room temperature will have a markeddegrading eifect on untreated wool. The more frequent the launderingsthe worse is the effect on the product. In order to simulate the efiectof the anticipated amount of laundering over the life of a wool garment,a test has been utilized in accordance with the following conditions:Sodium hydroxide solution of 0.1 N, i. e., tenth wool or fabric beingtested is immersed in this solution for a period of one hour at atemperature of 65C. In eflect, this is subjecting the material beingtested to a solution having a DH of about 13 and to a temperature far inexcess of the laundry maximum. A sample of ordinary wool, i. e.,untreated wool, when so treated showed an alkali solubility percent of10.5. Wool which had been reduced and alkylated with methylenedi-iodide, so that only half of the disulfide linkages had beenconverted to bis-thioether linkages, showed an alkali solubility of5.2%, and wool which had been reduced and alkylated to the same extentwith trimethylene dibromide showed an alkali solubility of 5.3% whensubjected to this rigorous test.

In short, the invention described in this appli simple process andproduces a chemically modified,.i. e., alkylated wool, which is superiorboth to untreated wool and to the oxidized or reduced wool of the priorart.

I claim:

1. The process oi treating animal fibers such as wool, hair, and furwhich contain keratin and which are characterized by having a pluralityof disulflde linkages in the molecule which comprises subjecting thematerial to the action oi a reducing agent of the group consisting oflower alkyl mercaptans, thioglycolic acid andbetamercaptoethanol whilemaintaining the pH 01' the reaction therefrom, then reacting theso-treated material with a compound oi the group consisting ofsubstituted and unsubstituted alkyl compounds containing at least twohalogens attached to aliphatic carbon atoms which do not have an acidicgroup attached thereto to convert the sulihydryl groups from thedisrupted disulflde linkages into mercaptoethanol while maintaining thepH oi the reaction below about pH 9 t disrupt at least some of thedisulfide linkages and form sulthydryl groups therefrom, then reactingthe sotreated material with an alkylene dihalide to convert thesulfhydryl groups from the disrupted disulfide linkages intobis-thioethers.

3. The process of treating wool which comprises sublecting the wool tothe action of a reducing agent of the group consisting of lower alkylmercaptans, thioglycolic acid and betamercaptoethanol while maintainingthe pH of the reaction below about pH 9 until a desired proportion ofthe disulflde linkages of the wool have been converted to sulfhydrylgroups, then treating the wool with a compound of the group consistingof substituted and unsubstituted alkyl compounds containing at least twohalogens attached to aliphatic carbon atoms which do not have an acidicgroup attached thereto to convert the sulihydryl groups intobis-thloethers.

4. The process of treating wool which comprises subjecting the wool tothe action of a reducingagent of the group consisting of lower alkylmercaptans, thioglycolic acid and betamercaptoethanol while maintainingthe pH of the reaction below about pH 9 until a desired proportion ofthe disulfide linkages f the wool have been converted to sulfhydrylgroups, then treating the wool with an alkylene dihalide to convert thesuli'hydryl groups into bisthioethers.

5. The process of treating wool which comprises subjecting the wool tothe action of a reducing agent of the group consisting of lower alkylmercaptans, thioglycolic acid and betamercaptoethanol while maintainingthe pH of the reaction at about pH 5 until a desired proportion of thedisulfide linkages of the wool have been converted to sulfhydryl groups,then treating the wool with a compound of the group consisting ofsubstituted and unsubstituted alkyl compounds containing at least twohalogens attached to aliphatic carbon atoms which do not have an acidicgroup attached thereto to convert the sulfhydryl groups intobisthioethers.

6. The process of treating wool which comprises subjecting the wool tothe action of a reducing agent of the group consisting of lower alkylmercaptans, thioglycolic acid and betamercaptoethanol while maintainingthe pH of the reaction below about pH 9 at a temperature of about 50 C.until a desired proportion of the disulfide linkages of the wool havebeen converted to sulfhydryl groups, then treating the asses wool with acompound of the group consisting of substituted and unsubstituted alkyicompounds containing at least two halogens attached to aliphatic carbonatoms which do no have an acidic group attached thereto to convert thesulihydryl groups into bis-thioethers.

7. The process of treating wool which comprises subjecting the wool tothe action of a reducing agent of the group consisting of lower alkylmercaptans, thioglycolic acid and betamercaptoethanol while maintainingthe pH of the reaction below about pH 9 until a desired proportion ofthe disulflde linkages oi the wool have been converted to sulthydrylgroups, then treating the wool at a pH between about pH 7 and about pH 9with a compound of the group consisting of substituted and unsubstitutedalkyl compounds containing at least two halogens attached to aliphaticcarbon atoms which do not have an acidic group attached thereto toconvert the sulfhydryl groups into bisthioethers.

8. The process of treating wool which comprises subjecting the wool tothe action of thioglycolic acid while maintaining the pH of the reactionbelow about pH 9 until a desired proportion or the disulfide linkages orthe wool have been converted to sulfhydryl groups, then treating thewool with a compound of the group consisting of substituted andunsubstituted alkyl compounds containing at least two halogens attachedto aliphatic carbon atoms which do not have an acidic group attachedthereto to convert the suifhydryl groups into bis-thioethers.

9. The process of treating wool which comprises subjecting the wool tothe action of thicglycolic acid while maintaining the pH of the reactionbelow about pH 9 until a desired proportion of the disulfide linkages ofthe wool have been converted to sulfhydryl groups, than treating thewool with an alkylene dihalide to convert the sulfhydryl groups intobis-thioethers.

10. An animal fiber oi the epidermal type such as wool, hair, and fur inwhich at least some of the disuifide linkages of the fiber molecule havebeen disrupted and converted to bis-thioethers oi the type representedby W-SRS-W' in which W and W' represent portions of the fiber moleculeto which the disrupted disulfide linkages are attached and R representsan alkylene nucleus having no acidic groups attached thereto.

11. Wool fiber in which at least some 0! the disulfide linkages of thewool molecule have been disrupted and converted to bis-thioethers of thetype represented by W-S-R-S-W' in which W and W represent portions orthe wool molecule to which the disrupted disulfide linkages are attachedand R represents an alkylene nucleus having no acidic groups attachedthereto.

MILTON HARRIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,261,094 Speakman Oct. 28, 19412,238,672 Arthur Apr. 15, 1941 2,253,102 Walker Aug. 19, 1941 2,131,146Schiack Sept. 2'7, 1938 2,261,294 Schiack Nov. 4, 1941 OTHER REFERENCES

